The 20-year-old Parisian spent a successful spell at Fulham in the Championship last season and will now continue his football education in Ligue 1.
Box-to-box midfielder Fofana made 25 appearances for the Cottagers, scoring one goal against Huddersfield.
Seko made two appearances in the first leg of City's recent first-team tour to Australia.
He played the second half of the 2-0 win over Adelaide United and came on as a late substitute in City's 1-0 win over Melbourne City.
Bastia, who are located in the Corsican region of France, finished 12th in the French top flight last season and are managed by Ghislain Printant.
We wish Seko all the best for his year-long stay in Ligue 1 and will keep you up to date with his progress in our weekly loan watch feature.
One to Watch: Seko Fofana